This application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 2000-233136, filed Aug. 1, 2000, the entire contents of which are incorporated herein by reference.
1. Field of the Invention
The present invention relates to an electronic apparatus using a fuel cell assembly as a power supply and, more particularly, to a personal computer using a fuel cell assembly of a type that directly oxidizes methanol.
2. Description of the Related Art
Various types of personal computers using fuel cell assembly have been proposed. In a personal computer using a conventional fuel cell assembly, the fuel cell assembly is mounted in the personal computer body.
Such a personal computer is disclosed in, for example, Jpn. Pat. Appln. KOKAI Publication No. 9-213359. The fuel cell assembly disclosed in Jpn. Pat. Appln. KOKAI Publication No. 9-213359 uses a hydrogen-absorbing metal.
In addition to a fuel cell assembly using a hydrogen-absorbing alloy, a DMFC (a fuel cell assembly designed to directly oxidize methanol) has been devised. Such a DMFC is disclosed in, for example, Japanese Patent Application No. 10-278759filed by the present applicant. A DMFC does not require so-called auxiliary equipment for a fuel system, and hence has no movable mechanical portion. For this reason, the DMFC is readily made compact and lightweight and can be optimally used as a power supply for a notebook personal computer (to be referred to as a notebook PC hereinafter)
If, however, a DMFC is designed not to have a stacked cell structure so as to manufacture the cell at a low cost, air supplied to the cell relies on diffusion and convection. As a consequence, to supply power required for a current notebook PC, the DMFC has an excessively large area. Even if the performance of a DMFC improves to, for example, 45 mW/cm2, the cell needs to have an area of 1,000 cm2 to supply 45 W. It is therefore the first challenge to incorporate a fuel cell assembly panel having the largest possible area into a notebook PC having limited outside dimensions and improve ventilation of the fuel cell assembly panel without using any ventilating fan.
The biggest merit in using a fuel cell assembly for a portable apparatus is that the apparatus can be used substantially unlimited while being out as long as a fuel is carried. However, the power that can be extracted from the fuel cell assembly is limited. If a high priority is to be given to the long-term use of a personal computer even at the expense of performance, the personal computer needs to be operated with a great restriction on power consumption. However, present notebook PCs are not designed to operate on the power that can be extracted from a fuel cell assembly. The second challenge is therefore to provide a notebook PC which can be used with a restriction imposed on power consumption without making the user misunderstand.
A fuel cell assembly essentially produces water. In general, this water is evaporated by using heat generated in the computer. It is, however, inevitable that evaporated steam is liquefied in the housing of the personal computer or the like, depending on environmental conditions. Designing a personal computer to prevent this water from entering the computer contradicts the requirements of heat dissipation, ventilation, and the like.
In a conventional personal computer, a fuel cell assembly is placed in the computer, and water produced by the fuel cell assembly enters the computer, resulting in a failure in the computer.
The present invention has been made in consideration of the above situation, and has as its object to provide an electronic apparatus which can incorporate a fuel cell assembly panel having a large area and provide good ventilation for the fuel cell assembly panel.
It is another object of the present invention to provide an electronic apparatus which can normally operate even on low power obtained from a fuel cell assembly.
In general, a notebook PC has a display unit which is rotatably mounted on the main body, and is usually rotated to nearly vertical when used. Since the display unit generally has an area near the upper limit within the notebook PC, it is reasonable that a fuel cell assembly panel requiring a large area is placed on the rear surface of the display unit. Since the display panel is often used at an angle near the right angle, convection effectively provides ventilation. Therefore, by placing the fuel cell assembly panel on the rear surface of the display unit, the first challenge can be achieved. Such an arrangement has already been indicated in H. L. Maynard et al., xe2x80x9cMiniaturized Fuel cell assembly for Portable Powerxe2x80x9d, 2nd Annual Advances in RandD for the commercialization of Small Fuel Cells and Battery Technologies for use in Portable Applications (Apr. 26-28, 2000).
The efficiency of a fuel cell assembly is generally high at a high temperature, and the fuel cell assembly generates heat equivalent to output power during operation. On the other hand, an LCD panel widely used for a display unit is susceptible to heat.
Since the cathode side of a fuel cell assembly panel requires oxygen, outside air is supplied thereto. Forming an air channel for supplying outside air on the LCD side will facilitate heat insulation between the fuel cell assembly and the LCD panel. This makes it possible to attain a reduction in cost. This is because, the temperature of the air channel is considerably lower than the temperature of the fuel cell assembly panel itself.
According to the first aspect of the present invention, there is provided an electronic apparatus comprising an electronic apparatus body, and a display unit rotatably mounted on the electronic apparatus body, wherein a fuel cell assembly for supplying power to the electronic apparatus and an air channel for supplying air to the fuel cell assembly are arranged in the display unit.
According to the second aspect of the present invention, there is provided a method of driving an electronic apparatus including an electronic apparatus body, and a display unit rotatably mounted on the electronic apparatus body, the display unit having a fuel cell assembly for supplying power to the electronic apparatus and a drain hole for draining water produced by the fuel cell assembly, comprising the steps of switching to a fuel cell assembly mode for using the fuel cell assembly, when it is detected that a tool for collecting water produced by the fuel cell assembly is connected to the drain hole, and a power supply of the electronic apparatus is in an OFF state, and executing a power supply ON sequence unique to the fuel cell assembly mode when the power supply of the electronic apparatus is turned on, and the output power of the fuel cell assembly reaches a predetermined value.
According to the present invention, the operation mode can be automatically switched to the fuel cell assembly mode only when a tool for collecting water produced by the fuel cell assembly is connected to the drain hole, and the electronic apparatus is in the OFF state. This prevents the user from making erroneous operation mode setting.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter.